T24? Chemistry. [Lecture 28. 



vessel*. When the fumes are corrosive, Jieiy 

 lutes must be used ; the best of which is pipe 

 clay mixed with seven times its quantity of white 

 sand. The clay only serves to combine the 

 particles of sand together, for sand resists the 

 most violent heat. A good luting for lining 

 the internal part of a furnace is made of char- 

 coal dust and water with one fourth of clay, 

 over which spread a covering of sand and clay, 

 and beat them well with a hammer. The char- 

 coal will last two or three years: the clay is 

 mixed with the charcoal to prevent its crack- 

 ing. 



Mr. Nicholson f most judiciously'remarks that 

 the ingenious student in chemistry, when he 

 has acquainted himself with the first principles, 

 will easily perceive that there are few philo- 

 sophical inquiries which require a large appa- 

 ratus of furnaces or vessels. A tobacco pipe 

 (the bore of which must be stopped with good 

 clay) is a very useful crucible, in which many 

 operations may be performed with a good pair 

 of double bellows. An earthen pot, or an iron 

 ladle, will contain a sand bath, and common 

 phials, or Florence flasks, serve very well for 



* When a bladder is used with the retort and receiver, 

 a hole may be made in it with a pin, by which the operator 

 may judge of the contents by the smell. 



-j- See his Dictionary of Chemistry. 



